{"id":"CVE-2026-89771","title":"kernel: ring-buffer: Fix subbuf resize race with ring buffer readers (CVE-2026-89771)","summary":"A flaw was found in the Linux kernel. A race condition exists in the ring buffer resizing mechanism, where `trace_buffer subbuf_size` can be read without proper locking while it is being simultaneously resized. This could allow a local att…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":"CWE-366","vendor":"Red Hat","product":"Red Hat Enterprise Linux 10","affected":["enterprise_linux 10","openshift_container_platform 4"],"published":"2026-09-11","updated":"2026-09-15","sourceUpdated":"2026-09-15T19:23:24+00:00","source":"CSAF","sourceUrl":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89771.json","references":[{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89771.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89771"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532138"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89771"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89771"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89771.mbox"},{"url":"https://git.kernel.org/stable/c/0c7c517827a453128a8f58bfd849546a29813b27"},{"url":"https://git.kernel.org/stable/c/50f4a793c4ff24826efb0ac700989a5063cc53df"},{"url":"https://git.kernel.org/stable/c/6d666f0b8b36c0765cf19fbe6de5a7ba5a73aad9"},{"url":"https://git.kernel.org/stable/c/8a5f63637890f03177146efddaba5ec7a1b4d61f"}],"tags":["csaf","vex","red-hat","cve.org","score-dispute"],"epss":0.0012,"epssPercentile":0.02064,"scores":{"vendor":4.7,"cna":7.8},"ingestedAt":"2026-09-14T15:23:07.472Z","slug":"CVE-2026-89771","body":"## Overview\n\nA flaw was found in the Linux kernel. A race condition exists in the ring buffer resizing mechanism, where `trace_buffer subbuf_size` can be read without proper locking while it is being simultaneously resized. This could allow a local attacker to trigger unpredictable behavior or a denial of service (DoS) by causing system instability.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat OpenShift Container Platform 4 · updated 2026-09-15 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89771.json)\n\n**kernel: ring-buffer: Fix subbuf resize race with ring buffer readers** — rated Moderate by Red Hat. Released 2026-09-11, updated 2026-09-15.\n\nAffected:\n\n- Red Hat Enterprise Linux 10\n- Red Hat OpenShift Container Platform 4\n\nNo fix planned:\n\n- Red Hat Enterprise Linux 10\n- Red Hat OpenShift Container Platform 4\n\nNot affected:\n\n- Red Hat Enterprise Linux 6\n- Red Hat Enterprise Linux 7\n- Red Hat Enterprise Linux 8\n- Red Hat Enterprise Linux 9\n- Red Hat OpenShift Container Platform 4\n\n## Remediation\n\nFix deferred","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":205526,"id":"CVE-2026-89771","ts":1789576723478,"field":"cvss","old":"4.7","new":"5.5"},{"seq":202950,"id":"CVE-2026-89771","ts":1789403733081,"field":"cvss","old":"7.8","new":"4.7"},{"seq":202949,"id":"CVE-2026-89771","ts":1789403733081,"field":"severity","old":"high","new":"medium"},{"seq":197653,"id":"CVE-2026-89771","ts":1789384318252,"field":"cvss","old":"4.7","new":"7.8"},{"seq":197652,"id":"CVE-2026-89771","ts":1789384318252,"field":"severity","old":"medium","new":"high"},{"seq":183639,"id":"CVE-2026-89771","ts":1789356676215,"field":"cvss","old":"7.8","new":"4.7"},{"seq":183638,"id":"CVE-2026-89771","ts":1789356676215,"field":"severity","old":"high","new":"medium"},{"seq":153660,"id":"CVE-2026-89771","ts":1789285351841,"field":"cvss","old":null,"new":"7.8"},{"seq":153659,"id":"CVE-2026-89771","ts":1789285351841,"field":"severity","old":"none","new":"high"},{"seq":147678,"id":"CVE-2026-89771","ts":1789270211849,"field":"cvss","old":null,"new":"4.7"},{"seq":147677,"id":"CVE-2026-89771","ts":1789270211849,"field":"severity","old":"none","new":"medium"},{"seq":109426,"id":"CVE-2026-89771","ts":1789183731867,"field":"cvss","old":null,"new":"4.7"},{"seq":109425,"id":"CVE-2026-89771","ts":1789183731867,"field":"severity","old":"none","new":"medium"}]}